Display device

ABSTRACT

A display device includes: a display panel that displays an image; a plurality of mount boards having long-length shaped disposed along the display panel; and light emitting elements arrayed on each of the plurality of mount boards in a longitudinal direction of each of the plurality of mount boards. The light emitting elements emit light toward the display panel from behind the display panel, and are arranged in a matrix shape along the display panel. The display device further includes: a back surface board on which the plurality of mount boards is stuck by an adhesive member; and a reflective sheet mounted to the back surface board. The reflective sheet has holes that allow the light emitting elements to pass through at positions corresponding to the light emitting elements, and reflects the light emitted from the light emitting elements toward the display panel. Each of the plurality of mount boards is constituted of a flexible wiring board.

TECHNICAL FIELD

The present disclosure relates to a display device that displays animage, such as a still image or a moving image.

BACKGROUND

As a display device, such as a television device or a computer monitor,there is a thin display device, of a liquid crystal panel, an organicelectro luminescence (EL) display panel, or the like.

A liquid crystal display device is a display device that does notspontaneously emit light. Therefore, in the liquid crystal displaydevice, light emitting elements, such as light emitting diodes (LEDs),are disposed on a back surface (a surface opposite to a surface viewedby a user) of a display panel included in the display device, and lightemitted from the LEDs and transmitted through the display panel reachesa user. Consequently, the user can visually recognize an image even in adark place or the like.

In the display device having this configuration, for example, lightemitting elements, such as LEDs, are arranged at intervals in a matrixshape. Accordingly, the display device may include a reflective sheetfor reflecting, to a display panel side, light that advances to a sideopposite to the display panel after being emitted from the lightemitting elements.

For example, PTL 1 discloses a display device in which a reflectivesheet is mounted on a back surface board.

CITATION LIST Patent Literature

PTL 1: Unexamined Japanese Patent Publication No. 2013-143218

SUMMARY

In a display device equipped with light emitting elements, such as LEDs,power supplied to the LEDs may be lost due to a heat loss of the LEDs.Alternatively, since a reflective sheet is lifted from a predeterminedposition to cause a gap on a rear surface side of the reflective sheet(hereinafter, this state is also referred to as a lift of the reflectivesheet), an optical loss (a partial loss of light emitted from the lightemitting elements) may occur.

The present disclosure is to provide a display device capable ofreducing a heat loss and an optical loss.

The display device according to the present disclosure includes: adisplay panel that displays an image; a plurality of mount boards havinglong-length shaped disposed along the display panel; and light emittingelements arrayed on each of the plurality of mount boards in alongitudinal direction of each of the plurality of mount boards. Thelight emitting elements emit light toward the display panel from behindthe display panel, and are arranged in a matrix shape along the displaypanel. The display device further includes: a back surface board onwhich the plurality of mount boards is stuck by an adhesive member; anda reflective sheet mounted to the back surface board. The reflectivesheet has holes that allow the light emitting elements to pass throughat positions corresponding to the light emitting elements, and reflectsthe light emitted from the light emitting elements toward the displaypanel. In the display device, each of the plurality of mount boards isconstituted of a flexible wiring board.

The display device according to the present disclosure can reduce a heatloss and an optical loss.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view schematically illustrating an example of anexternal appearance of a display device according to a first exemplaryembodiment.

FIG. 2 is an exploded perspective view schematically illustrating anexample of a structure of the display device according to the firstexemplary embodiment.

FIG. 3 is a view schematically illustrating a configuration example of alight emitting element and a mount board that configure a light emittingmodule according to the first exemplary embodiment.

FIG. 4 is a view schematically illustrating an example of a relay boardthat configures the light emitting module according to the firstexemplary embodiment.

FIG. 5 is a view schematically illustrating an example of a reflectivesheet according to the first exemplary embodiment.

FIG. 6 is a view illustrating a part of the reflective sheet in anenlarged manner according to the first exemplary embodiment.

FIG. 7 is a view schematically illustrating an example of a back surfaceboard according to the first exemplary embodiment.

FIG. 8 is a partially sectional view schematically illustrating aconfiguration example of a recess of the back surface board according tothe first exemplary embodiment.

FIG. 9 is a schematic view for describing a lift of a reflective sheetfrom a mount board according to a comparative example.

FIG. 10 is a schematic view for describing overlapping of the reflectivesheet and the mount board according to the first exemplary embodiment.

DESCRIPTION OF EMBODIMENT

Hereinafter, an exemplary embodiment will be described in detail withreference to the drawings as appropriate. However, detailed descriptionsthat are more than necessary may be omitted. For example, a detaileddescription of a matter that has been already known well, or anoverlapped description for a substantially identical configuration maybe omitted. This is to avoid unnecessary redundancy of the followingdescription and facilitate the understanding of those skilled in theart.

Note that the attached drawings and the following description areprovided for those skilled in the art to fully understand the presentdisclosure, and only indicate an example of a display device accordingto the present disclosure. Therefore, the attached drawings and thefollowing description are not intended to limit the subject matter asdescribed in the claims. The scope of the present disclosure is definedby the recitations in the claims with the following exemplary embodimentused as a reference and thus is not limited to the following exemplaryembodiment only. Therefore, among components in the following exemplaryembodiment, components that are not recited in an independent claimindicating the most generic concept of the present disclosure are notnecessarily essential for achievement of the object of the presentdisclosure but are described as preferable components.

In addition, the drawings are not always strictly illustrated, and areschematic views in which emphasis, omission, and proportion adjustmentare made as appropriate for illustration of the present disclosure. Thedrawings may have shapes, positional relationships and proportions thatdiffer from actual shapes, actual positional relationships, and actualproportions. Further, in the drawings, substantially identicalcomponents are denoted by identical reference marks, and descriptions ofthose components may be omitted or simplified.

First Exemplary Embodiment [1-1. Outline of Configuration of DisplayDevice]

FIG. 1 is a perspective view schematically illustrating an example of anexternal appearance of display device 100 according to a first exemplaryembodiment.

FIG. 2 is an exploded perspective view schematically illustrating anexample of a structure of display device 100 according to the firstexemplary embodiment.

Note that FIGS. 1 and 2 schematically illustrate a rough configurationof display device 100, and details of the configuration are omitted.

Note that, hereinafter, an X-axis, a Y-axis, and a Z-axis are used asrequired to describe the present exemplary embodiment. In the presentexemplary embodiment, for the sake of convenience, a direction parallel(substantially parallel) to a longitudinal direction of display device100 is defined as the X-axis, a direction parallel (substantiallyparallel) to a short direction of display device 100 is defined as theY-axis, and a direction orthogonal to both the X-axis and the Y-axis isdefined as the Z-axis. Further, a vertical direction to an X-Z plane,that is, a Y-axis direction, is a gravity direction. Under an ordinaryuse condition, display device 100 is installed on an installationsurface parallel (substantially parallel) to the X-Z plane. Further, aside facing a user (not illustrated) who watches display device 100 isdefined as a “front surface”, and a side opposite to the front surfaceis defined as a “back surface”. A side relatively far from theinstallation surface in the Y-axis direction is defined as a “top”, anda side relatively close to the installation surface in the Y-axisdirection is defined as a “bottom”. Note that these directions arerelative directions illustrated conveniently, and are not absolutedirections.

Display device 100 includes frame body 101, front surface member 102,display panel 103, light emitting unit 140, back surface board 108, andback surface cover 109.

Display device 100 described in the present exemplary embodiment is, forexample, a television device that outputs an image and a sound obtainedfrom a received broadcast wave, and includes a circuit board (notillustrated) or the like inside. Note that, since a configuration of thetelevision device is substantially identical to a generally knownconfiguration, description of the configuration is omitted.

Frame body 101, front surface member 102, and back surface cover 109 aremembers that cover display panel 103, light emitting unit 140, and thelike. Frame body 101 is a member that protects an outer periphery ofdisplay panel 103 and the like. Front surface member 102 is atransparent member that covers a front surface of display panel 103.Back surface cover 109 is a member that protects a back surface ofdisplay panel 103 and the like.

Display panel 103 is a device that displays an image based on an inputimage signal. The image includes a still image, a moving image, and thelike. The image also includes a character, a symbol, and the like.Display panel 103 described in the present exemplary embodiment is aliquid crystal display panel. Further, a thickness of display panel 103ranges approximately from 1 mm to 3 mm, inclusive, for example. Notethat a kind of display panel 103 is not particularly limited in thepresent disclosure. Any kind of display panel 103 may be used as long asdisplay panel 103 requires light transmitted through display panel 103when displaying an image.

Light emitting unit 140 is a member for emitting light havingsubstantially uniform brightness to the back surface of display panel103. Light emitting unit 140 is generally referred to as a “backlight”or the like. Light emitting unit 140 includes diffuser panel 104,reflective sheet 105, and light emitting module 106.

[1-2. Light Emitting Module]

FIG. 3 is a view schematically illustrating a configuration example oflight emitting element 161 and mount board 162 that configure lightemitting module 106 according to the first exemplary embodiment.

FIG. 4 is a view schematically illustrating an example of relay board163 that configures light emitting module 106 according to the firstexemplary embodiment.

As illustrated in FIGS. 3 and 4, light emitting module 106 includesmount board 162, light emitting element 161, and relay board 163. Aplurality of mount boards 162 having long-length shapes (long-lengthshapes in the Y-axis direction) is disposed along a longitudinaldirection (the X-axis direction) and a short direction (the Y-axisdirection) of display panel 103. A plurality of light emitting elements161 is arrayed on each mount board 162 along a longitudinal direction(the Y-axis direction) of mount board 162. Relay board 163 iselectrically connected to each of the plurality of mount boards 162.

(1-2-1. Mount Board)

Mount board 162 is a member used to facilitate arrangement of lightemitting element 161 for back surface board 108. The plurality of lightemitting elements 161 is arrayed on each mount board 162 along thelongitudinal direction (the Y-axis direction) of mount board 162.Moreover, since mount boards 162 are placed on display panel 103 in amatrix shape as illustrated in FIG. 3, the plurality of light emittingelements 161 is arranged in a matrix shape along the longitudinaldirection (the X-axis direction) and the short direction (the Y-axisdirection) of display panel 103.

Mount board 162 includes contact point 162 a electrically connected torelay board 163 and a conductive member (not illustrated) thatelectrically interconnects contact point 162 a and each light emittingelement 161. This conductive member is printed wiring, for example. Ineach mount board 162, power is supplied to each light emitting element161 from relay board 163 electrically connected to contact point 162 a.With this configuration, each light emitting element 161 mounted tomount board 162 is lit.

As mentioned above, in the present exemplary embodiment, the pluralityof light emitting elements 161 is arrayed in a row on mount board 162 inthe longitudinal direction of mount board 162. Mount board 162 isconstituted of a long-length shaped flexible wiring board having athickness ranging from 0.01 mm to 0.05 mm, inclusive, for example.Further, mount board 162 is stuck on back surface board 108 by anadhesive member (for example, a double-sided tape). Note that theflexible wiring board is a board in which an electric circuit isprovided on a base material formed by sticking a thin and soft base filmhaving insulation properties, such as polyimide, and a conductive metal,such as a copper foil. The flexible wiring board has flexibility.Further, the adhesive member may be an adhesive agent or the like.

An arrangement position of each mount board 162 is set such that an endincluding contact point 162 a is disposed in recess 1081 (see FIG. 7) ofback surface board 108, which will be described below. Accordingly, eachmount board 162 is placed on back surface board 108. Then, a backsurface of the end including contact point 162 a of mount board 162 isstuck on recess 1081 by, for example, a double-sided tape.

Further, in each mount board 162, a layer having a light reflectancehigher than a light reflectance of a body of mount board 162 is providedon a surface, on which light emitting elements 161 are arrayed, among aplurality of surfaces included in mount board 162. In the presentexemplary embodiment, since a white solder resist is applied to thesurface (the surface on which light emitting elements 161 are arrayed)of mount board 162, white resist film 162 b (of a highly reflectivetype) having a light reflectance of 95% or more is formed as a layerhaving a high light reflectance. In the present exemplary embodiment,the light reflectance of resist film 162 b may be 99.9%, for example.Note that a light reflectance of a generally known white resist film isabout 90%.

(1-2-2. Light Emitting Element)

As mentioned above, the plurality of light emitting elements 161 isarrayed on each mount board 162 along the longitudinal direction (theY-axis direction) of each mount board 162. Moreover, each light emittingelement 161 emits light from behind display panel 103 toward displaypanel 103. In display device 100, since mount boards 162 are placedalong the longitudinal direction (the X-axis direction) and the shortdirection (the Y-axis direction) of display panel 103, respectively, theplurality of light emitting elements 161 is arranged in the matrix shapealong the longitudinal direction (the X-axis direction) and the shortdirection (the Y-axis direction) of display panel 103, respectively.

Note that a kind of light emitting element 161 is not particularlylimited. For example, a white LED that emits white light may be used aslight emitting element 161. The white LED can be realized by, forexample, combining a blue light emitting diode and a fluorescentmaterial that emits yellow light.

(1-2-3. Relay Board)

As illustrated in FIG. 4, for example, relay board 163 is constituted ofa printed wiring board having a long-length shape (a long-length shapein the X-axis direction). Relay board 163 is a board used to supplypower to light emitting element 161. Relay board 163 is placed in recess1081 provided on back surface board 108 (see FIG. 7) such that the end(the end including contact point 162 a) of mount board 162 is heldbetween relay board 163 and back surface board 108. With thisconfiguration, relay board 163 is in contact with the end (the endincluding contact point 162 a) of mount board 162 disposed in recess1081, and is electrically connected with contact point 162 a of mountboard 162. In other words, relay board 163 is placed in recess 1081 soas to be in contact with the end including contact point 162 a of mountboard 162, and is physically in contact with contact point 162 a ofmount board 162. Accordingly, relay board 163 is electrically connectedwith contact point 162 a.

In the present exemplary embodiment, relay board 163 is, for example,constituted of a long-length shaped rigid board having a thicknessappropriately ranging from 0.08 mm to 1.0 mm, inclusive. Further, relayboard 163 is formed, on a surface on a side that is in contact withmount board 162 (a surface on a Z-axis negative direction side), withwiring for supplying power to light emitting element 161 through contactpoint 162 a of mount board 162. Further, relay board 163 is providedwith through-hole 1631 for fixing relay board 163 to back surface board108 by a screw or the like.

Note that relay board 163 may be configured with a flexible wiringboard. In a case of this configuration, recess 1081 may not be providedon back surface board 108, and through-hole 1631 may not be provided inrelay board 163.

(1-3. Diffuser Panel)

Diffuser panel 104 is a member that diffuses light emitted from eachlight emitting element 161. For example, diffuser panel 104 is aplate-shaped transparent member having minute irregularity on only oneside or both sides of diffuser panel 104. For example, diffuser panel104 diffuses and emits light entered from a back surface side ofdiffuser panel 104 to substantially all directions from a front surfaceside of diffuser panel 104. With this configuration, diffuser panel 104reduces visual angle dependency on brightness of light emitted fromlight emitting unit 140 (brightness of light that reaches a user ischanged depending on an angle of display device 100 viewed by the user),and substantially equalizes the brightness of light emitted from lightemitting unit 140.

Note that a configuration of diffuser panel 104 is not limited to theabove-described configuration. For example, fine particles having a highoptical reflectance may be dispersed and disposed inside diffuser panel104.

Alternatively, diffuser panel 104 may be formed by overlapping aplurality of films having minute irregularity.

(1-4. Reflective Sheet)

FIG. 5 is a view schematically illustrating an example of reflectivesheet 105 according to the first exemplary embodiment. FIG. 5illustrates reflective sheet 105 before being mounted to back surfaceboard 108.

FIG. 6 is a view illustrating a part of reflective sheet 105 in anenlarged manner according to the first exemplary embodiment. FIG. 6illustrates the part of reflective sheet 105 in an enlarged manner afterbeing mounted to back surface board 108. Note that FIG. 6 illustratesarea “a” surrounded by a broken line in FIG. 5.

Reflective sheet 105 has a plurality of holes 151. Reflective sheet 105is mounted to back surface board 108 such that light emitting element161 disposed on a surface of light emitting module 106 facing a backsurface side of reflective sheet 105 is exposed to a front surface sideof reflective sheet 105 through hole 151. Then, reflective sheet 105reflects, among light beams emitted from light emitting element 161, alight beam that advances in a back surface direction (the Z-axisnegative direction) toward display panel 103 (to a Z-axis positivedirection side). Note that a material for forming reflective sheet 105is not particularly limited. For example, a sheet member formed ofsynthetic resin, such as white polyethylene terephthalate (PET)excellent in light reflectivity, can be used for reflective sheet 105.

As illustrated in an example in FIG. 6, reflective sheet 105 has theplurality of (for example, a same number as a number of light emittingelements 161) holes 151 for allowing light emitting elements 161 to passthrough at positions corresponding to light emitting elements 161 ofmount boards 162 disposed on back surface board 108. Specifically, inreflective sheet 105, hole 151 that is larger than an outer shape oflight emitting element 161 is provided at a position corresponding toeach light emitting element 161 of mount boards 162 disposed on backsurface board 108. Then, when reflective sheet 105 is mounted to backsurface board 108, light emitting element 161 is inserted into hole 151.Note that each drawing illustrates an example in which hole 151 isformed in a quadrangular shape. However, hole 151 may be formed in ashape other than the quadrangular shape, such as a circular shape.

In the present exemplary embodiment, white resist film 162 b (of thehighly reflective type) having the light reflectance of 95% or more isformed on mount board 162. Accordingly, even when a part of a surface ofmount board 162 (resist film 162 b around light emitting element 161) isexposed from hole 151, resist film 162 b can reflect the light fromlight emitting element 161 at relatively high light reflectance. Withthis configuration, in the present exemplary embodiment, a size of hole151 can be made larger than the outer shape of light emitting element161, as illustrated in FIG. 6. Specifically, in the present exemplaryembodiment, when a size of light emitting element 161 in a top viewranges from 1 mm square to 3 mm square, inclusive, the size of hole 151in the top view (the size of hole 151 when hole 151 is seen from theZ-axis positive direction side) is set so as to be ranging from 10 mmsquare to 15 mm square, inclusive (that is, 9 times or more of the outershape (the size when viewed from the top) of light emitting element161). Accordingly, in the present exemplary embodiment, light emittingelement 161 is exposed from hole 151 of reflective sheet 105, and a partof white resist film 162 b applied to mount board 162 (resist film 162 baround light emitting element 161) is exposed from hole 151.

To compare with the present exemplary embodiment, a case where a lightreflectance of a white resist film formed on mount board 162 is lessthan 95% (that is, a resist film that is not a highly reflective type isformed on mount board 162) is assumed. Alternatively, a case where whiteresist film 162 b is not formed on mount board 162 is assumed. In suchcase, the surface of mount board 162 can only reflect the light fromlight emitting element 161 at a relatively low light reflectance.Therefore, in order to suppress an optical loss caused by exposure ofthe surface of mount board 162 having the relatively low lightreflectance from hole 151, it is necessary to form the size of hole 151almost equal to the outer shape of light emitting element 161, in such away that the surface of mount board 162 around light emitting element161 is not exposed from hole 151 as much as possible. For example, whenthe size of the outer shape of light emitting element 161 in the topview ranges from 1 mm square to 3 mm square, inclusive, exposure of thesurface of mount board 162 around light emitting element 161 from hole151 can be prevented by forming hole 151 with a size ranging from 1 mmsquare to 3 mm square, inclusive that is almost equal to the outer shapeof light emitting element 161. However, in this configuration, whenreflective sheet 105 is mounted to back surface board 108, it isdifficult to insert light emitting element 161 into hole 151. Moreover,upon mounting of reflective sheet 105 to back surface board 108, an edgeof hole 151 can be turned up when the edge of hole 151 touches or rubsagainst light emitting element 161. Accordingly, a lift (a lift frommount board 162) can occur on reflective sheet 105. Moreover, because ofoccurrence of such a lift, the light from light emitting element 161 canenter a gap caused by the lift, thereby causing an optical loss. Bymaking the size of hole 151 sufficiently larger than the outer shape oflight emitting element 161, light emitting element 161 is easilyinserted into hole 151, and occurrence of the lift can be prevented.However, in this case, the surface of mount board 162 having therelatively low light reflectance is exposed from hole 151 of reflectivesheet 105. Therefore, in order to suppress an optical loss in this case,for example, it is necessary that the surface of mount board 162 exposedfrom hole 151 is covered with a piece of reflective sheet by stickingthe piece of reflective sheet on mount board 162 so as to surround lightemitting element 161.

In the present exemplary embodiment, since white resist film 162 bhaving the relatively high light reflectance (95% or more) is formed onthe surface of mount board 162, even when the surface of mount board 162is exposed from hole 151, an exposed area may not be covered with thepiece of reflective sheet. In other words, in reflective sheet 105, thesize of hole 151 can be made larger than the outer shape of lightemitting element 161, thereby providing an ample space.

Reflective sheet 105 is stuck and fixed to back surface board 108 by adouble-sided tape or the like. At this time, in display device 100, whenreflective sheet 105 mounted to back surface board 108 is viewed fromthe front surface side (the Z-axis positive direction side) (that is,when viewed from the top), an end of mount board 162 and an end of hole151 corresponding to the end of mount board 162 overlap each other (notillustrated). In other words, when viewed from the front surface side,reflective sheet 105 mounted to back surface board 108 has an area thatoverlaps with mount board 162 and an area that does not overlap withmount board 162 and is in contact with (or faces) back surface board108. Moreover, the area of reflective sheet 105 that overlaps with mountboard 162 near hole 151 is extruded to the front surface side by mountboard 162. Note that reflective sheet 105 may have flexibility(elasticity) that can be bulged out (deformed) when a part of reflectivesheet 105 is extruded.

In the present exemplary embodiment, mount board 162 is formed of along-length shaped and comparatively thin (for example, a thicknessranging from 0.01 mm to 0.05 mm, inclusive) flexible wiring board.Further, the size of hole 151 is larger than the outer shape of lightemitting element 161, thereby providing an ample space. Accordingly,when reflective sheet 105 is stuck on back surface board 108, eventhough the area of reflective sheet 105 that overlaps with mount board162 is slightly extruded to the front surface side, reflective sheet 105is not bulged out (deformed). To compare with the present exemplaryembodiment, a case where the thickness of mount board 162 is relativelylarge is assumed. In this case, the area of reflective sheet 105 thatoverlaps with mount board 162 is extruded to the front surface side, anda lift (a lift from mount board 162) of reflective sheet 105 can occurat an edge of hole 151. Then, the aforementioned optical loss can occurdue to this lift. To suppress this optical loss, it is necessary thatthe lift is suppressed by sticking a piece of the reflective sheet onreflective sheet 105 and a surface of mount board 162 over the edge ofhole 151, for example. In the present exemplary embodiment, since mountboard 162 is formed of the flexible wiring board as mentioned above,when reflective sheet 105 is stuck on back surface board 108 by adouble-sided tape or the like, the lift from mount board 162 of the areaof reflective sheet 105 that overlaps with mount board 162 issuppressed. Accordingly, it is not necessary to use the above-describedpiece of reflective sheet or the like for suppressing the lift ofreflective sheet 105.

[1-5. Back Surface Board]

FIG. 7 is a view schematically illustrating an example of back surfaceboard 108 according to the first exemplary embodiment. FIG. 7illustrates back surface board 108 before light emitting unit 140 ismounted.

FIG. 8 is a partially sectional view schematically illustrating aconfiguration example of recess 1081 of back surface board 108 accordingto the first exemplary embodiment. FIG. 8 illustrates an outline of aninside of recess 1081 after light emitting unit 140 is mounted.

Back surface board 108 is a plate-shaped member that holds display panel103. As shown in FIG. 2, back surface board 108 is disposed on the backsurface (a surface on the Z-axis negative direction side) of displaypanel 103. Further, back surface board 108 holds light emitting unit 140between display panel 103 and back surface board 108, and holds acircuit board (not illustrated) or the like on a back surface of backsurface board 108. For example, back surface board 108 is formed byusing a metal plate material generally referred to as a “chassis”.Further, irregularity is provided on back surface board 108 by pressworking or the like to improve structural strength or the like.

In the present exemplary embodiment, back surface board 108 includesrecess 1081 and hole 1082.

Recess 1081 is provided in a long-length shape in a longitudinaldirection (the X-axis direction) of back surface board 108. For example,as illustrated in FIG. 8, relay board 163 and one end (an end includingcontact point 162 a) of mount board 162 are placed in recess 1081. Adepth (a size in the Z-axis direction) of recess 1081 is, for example,set so as to be almost equal to a size in which a thickness of mountboard 162 is added to a thickness of relay board 163. Note that, in thepresent exemplary embodiment, as illustrated in FIG. 8, mount board 162is stuck on back surface board 108 by double-sided tape 107. Moreover,since mount board 162 has flexibility, the one end (the end includingcontact point 162 a) of mount board 162 is also stuck on back surfaceboard 108 by double-sided tape 107 even in recess 1081. In this way, theone end of mount board 162 is placed in recess 1081.

Hole 1082 is used to electrically connect the circuit board (notillustrated) or the like held on the back surface of back surface board108 and relay board 163 (for example, to pass through electricalwiring).

Note that a boss for screwing or the like may be mounted to back surfaceboard 108. Further, back surface board 108 may be disposed so as tocover an entire surface (or an almost entire surface) of the backsurface of display panel 103, or may have a function of radiating heatgenerated from display panel 103.

[1-6. Effects and Others]

As described above, in the present exemplary embodiment, a displaydevice includes: a display panel that displays an image; a plurality ofmount boards having long-length shaped disposed along the display panel;and light emitting elements arrayed on each of the plurality of mountboards in a longitudinal direction of each of the plurality of mountboards. The light emitting elements emit light toward the display panelfrom behind the display panel, and are arranged in a matrix shape alongthe display panel. The display device further includes: a back surfaceboard on which the plurality of mount boards is stuck by an adhesivemember; and a reflective sheet mounted to the back surface board. Thereflective sheet has holes that allow the light emitting elements topass through at the positions corresponding to the light emittingelements, and reflects the light emitted from the light emittingelements toward the display panel. Each of the plurality of mount boardsis constituted of a flexible wiring board.

Note that display device 100 is an example of the display device.Display panel 103 is an example of the display panel. Mount board 162 isan example of the mount board. Light emitting element 161 is an exampleof the light emitting element. Double-sided tape 107 is an example ofthe adhesive member. Back surface board 108 is an example of the backsurface board. Hole 151 is an example of the hole that allows the lightemitting element to pass through. Reflective sheet 105 is an example ofthe reflective sheet.

The display device configured in this way can reduce a heat loss and anoptical loss.

For example, display device 100 described in the first exemplaryembodiment includes: display panel 103 that displays an image; theplurality of long-length shaped mount boards 162 disposed along displaypanel 103; and light emitting elements 161 arrayed on each of theplurality of mount boards 162 in the longitudinal direction of each ofthe plurality of mount boards 162. Light emitting elements 161 emitlight toward display panel 103 from behind display panel 103, and arearranged in a matrix shape along display panel 103. Display device 100further includes: back surface board 108 on which the plurality of mountboards 162 is stuck by double-sided tape 107; and reflective sheet 105mounted to back surface board 108. Reflective sheet 105 has holes 151that allow light emitting elements 161 to pass through at the positionscorresponding to light emitting elements 161, and reflects the lightemitted from light emitting elements 161 toward display panel 103. Eachof the plurality of mount boards 162 is constituted of the flexiblewiring board.

Therefore, display device 100 can reduce a heat loss and an opticalloss.

In the display device according to the present exemplary embodiment, athickness of the flexible wiring board may range from 0.01 mm to 0.05mm, inclusive.

In display device 100 configured in this way, mount board 162 isconstituted of the long-length shaped relatively thin flexible wiringboard. Accordingly, thermal resistance in mount board 162 can be greatlyreduced, compared with a case where a mount board is constituted of along-length shaped rigid board having a thickness of about 1 mm. Withthis configuration, in display device 100, the heat generated from lightemitting element 161 can also be radiated from mount board 162, therebyreducing the heat loss.

Further, in display device 100 configured as above, mount board 162 canbe stuck on back surface board 108 by a double-sided tape or the like,without providing a recess for placing mount board 162 on back surfaceboard 108. Moreover, a lift of reflective sheet 105 can be alsosuppressed. With this configuration, display device 100 can suppress anoptical loss caused by the lift of reflective sheet 105. This effectwill be described with reference to FIGS. 9 and 10.

FIG. 9 is a schematic view for describing a lift of reflective sheet 105from mount board 562 according to a comparative example.

FIG. 10 is a schematic view for describing overlapping of reflectivesheet 105 and mount board 162 according to the first exemplaryembodiment.

The comparative example shown in FIG. 9 illustrates an example in whichmount board 562 is constituted of a long-length shaped rigid boardhaving a thickness of 1 mm. In the comparative example shown in FIG. 9,a recess for placing mount board 562 is provided on back surface board508. This recess is provided to suppress the lift of reflective sheet105. Without this recess, as mentioned above, the lift of reflectivesheet 105 can occur due to the thickness of mount board 562. This recessis set at a depth (a size in a Z-axis direction) according to thethickness of mount board 562, and is formed on back surface board 508 bypress working, for example. However, it is difficult to form this recesswith high precision by the press working For example, if the depth ofthis recess is smaller than a set value, mount board 562 protrudes fromthe recess to a front surface side (a Z-axis positive direction side).Accordingly, the lift of reflective sheet 105 can occur, as mentionedabove. Alternatively, if the depth of this recess is larger than the setvalue, as illustrated in FIG. 9, when mount board 562 is stuck andplaced on this recess by double-sided tape 107, a gap is generatedbetween a surface of mount board 562 and reflective sheet 105.Accordingly, the lift of reflective sheet 105 can occur. Moreover, whenthese lifts of reflective sheet 105 occur, light from light emittingelements 161 arrayed on mount board 562 enters the gap caused by thelift, thereby causing an optical loss.

On the other hand, as illustrated in FIG. 10, in the present exemplaryembodiment, mount board 162 is constituted of a relatively thin (forexample, a thickness ranging from 0.01 mm to 0.05 mm, inclusive)flexible wiring board. Accordingly, there is no need to provide therecess, as illustrated in FIG. 9, for placing mount board 162 on backsurface board 108, and a process and a cost required for manufacturingdisplay device 100 can be suppressed. Moreover, even if the recess asillustrated in FIG. 9 is not provided on back surface board 108,occurrence of a lift of reflective sheet 105 is suppressed, and mountboard 162 can be stuck on back surface board 108 by double-sided tape107 directly (that is, without providing a recess). Note that, even ifmount board 162 extrudes a part of reflective sheet 105 near hole 151 tothe front surface side (the Z-axis positive direction side) (that is, abulge occurs near hole 151 of reflective sheet 105) due to the thicknessof mount board 162, mount board 162 is relatively thin and, for example,only has a thickness ranging approximately from 0.01 mm to 0.05 mm,inclusive. Accordingly, even if a lift of reflective sheet 105 occurs,the lift can be kept small so as to cause substantially no problem.

In this way, in display device 100 of the present exemplary embodiment,since mount board 162 has the above-described configuration, the lift ofreflective sheet 105 is prevented, and the optical loss caused by thelift of reflective sheet 105 can be reduced.

In the display device according to the present exemplary embodiment, awhite solder resist having a light reflectance of 95% or more may beapplied to the surface, on which the light emitting elements arearrayed, among a plurality of surfaces included in each of the pluralityof mount boards.

In the display device according to the present exemplary embodiment,when a size of each of the light emitting elements in a top view rangesfrom 1 mm square to 3 mm square, inclusive, a size of each of the holesin the top view may range from 10 mm square to 15 mm square, inclusive.

Note that resist film 162 b is an example of the film formed by applyingthe white solder resist having the light reflectance of 95% or more.

For example, in display device 100, the white solder resist having thelight reflectance of 95% or more is applied to the surface, on whichlight emitting elements 161 are arrayed, among the plurality of surfacesincluded in each of the plurality of mount boards 162. Accordingly,resist film 162 b is formed. Further, when the size of each of lightemitting elements 161 in the top view ranges from 1 mm square to 3 mmsquare, inclusive, the size of each of holes 151 in the top view rangesfrom 10 mm square to 15 mm square, inclusive.

In display device 100 configured in this way, the size of hole 151provided in reflective sheet 105 is considerably larger than the outershape of light emitting element 161. Accordingly, the area in whichmount board 162 and reflective sheet 105 overlap each other can bereduced. With this configuration, since the lift of reflective sheet 105can be further suppressed, the optical loss caused by the lift ofreflective sheet 105 can be reduced.

In the display device according to the present exemplary embodiment, thereflective sheet may be stuck on the back surface board by the adhesivemember. Further, an end of each of the plurality of mount boards and anend of each of holes, among the holes, corresponding to the end of eachof the plurality of mount boards may overlap each other when viewed fromthe top.

For example, in display device 100, reflective sheet 105 may be stuck onback surface board 108 by double-sided tape 107. Further, the end ofeach of the plurality of mount boards 162 and the end of each of holes151 corresponding to the end of each of the plurality of mount boards162 may overlap each other when viewed from the top. In display device100 configured in this way, double-sided tape 107 for fixing mount board162 can be also used for fixing reflective sheet 105.

The display device according to the present exemplary embodiment mayfurther include a relay board having a long-length shape for supplyingpower to the light emitting elements. In the display device, on asurface of the back surface board on which the plurality of mount boardsis stuck, a recess depressed toward an opposite surface of the surfaceon which the plurality of mount boards is stuck may be provided in adirection perpendicular to the longitudinal direction of each of theplurality of mount boards. Moreover, in the display device, when therelay board is placed in the recess, and is placed at an end of each ofthe plurality of mount boards located in the recess, the relay board maybe electrically connected with each of the plurality of mount boards.

Note that relay board 163 is an example of the relay board. Recess 1081is an example of the recess.

For example, display device 100 according to the present exemplaryembodiment further includes long-length shaped relay board 163 forsupplying power to light emitting elements 161. In display device 100,on the surface of back surface board 108 on which the plurality of mountboards 162 is stuck, recess 1081 depressed toward an opposite surface ofthe surface on which the plurality of mount boards 162 is stuck isprovided in the direction perpendicular to the longitudinal direction ofeach of the plurality of mount boards 162. Moreover, in display device100, relay board 163 is placed in recess 1081, and is placed at the endof each of the plurality of mount boards 162 located in recess 1081.Accordingly, relay board 163 is electrically connected with each of theplurality of mount boards 162.

In this way, in display device 100 of the present exemplary embodiment,relay board 163 can be placed in recess 1081 by providing recess 1081 onback surface board 108. Moreover, since mount board 162 is constitutedof the flexible wiring board having flexibility, the end (the endincluding contact point 162 a) of mount board 162 can be deformed alongthe shape of recess 1081 and placed in recess 1081. With thisconfiguration, in display device 100, since an electrically connectedportion between relay board 163 and mount board 162 can be disposed inrecess 1081, relay board 163 that supplies power to mount board 162 canrealize a configuration that does not push up reflective sheet 105.Accordingly, in display device 100, bending or the like of reflectivesheet 105 hardly occurs, and spots of reflected light caused by thebending or the like of reflective sheet 105 can be reduced.

Other Exemplary Embodiments

As described above, the first exemplary embodiment has been described toexemplify the technique in the present disclosure. The accompanyingdrawings and detailed description are provided for the description.

However, the present disclosure is not limited to the above-mentionedexemplary embodiment. The components described in the accompanyingdrawings and the detailed description may include not only thecomponents essential for solving the problem but also components thatare not essential for solving the problem in order to illustrate theabove-described technique. For this reason, those nonessentialcomponents that are illustrated in the accompanying drawings and aredescribed in the detailed description should not be immediatelyacknowledged as essential.

Further, since the above exemplary embodiment exemplifies the techniquein the present disclosure, various modifications, substitutions,additions and omissions can be performed within the scope of claims andequivalent scope of claims. In addition, new exemplary embodiments canbe made by combining components described in the first exemplaryembodiment. In addition, other exemplary embodiments implemented byexcluding some of the components may become exemplary embodiments of thepresent disclosure. In addition, modifications obtainable throughvarious changes to the above exemplary embodiment that are conceived bythose skilled in the art without departing from the essence of thepresent disclosure, that is to say, the meaning of the recitations inthe claims are also included in the present disclosure.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to a display device that displaysan image, a character, a moving image, or the like, by using abacklight. Specifically, the present disclosure is applicable to anelectronic device, such as a television device, a monitor, a digitalsignage, a mobile terminal, a tablet terminal, or a table type displaydevice.

REFERENCE MARKS IN THE DRAWINGS

100: display device

101: frame body

102: front surface member

103: display panel

104: diffuser panel

105: reflective sheet

106: light emitting module

107: double-sided tape

108, 508: back surface board

109: back surface cover

140: light emitting unit

151, 1082: hole

161: light emitting element

162, 562: mount board

162 a: contact point

162 b: resist film

163: relay board

1081: recess

1631: through-hole

1. A display device comprising: a display panel that displays an image;a plurality of mount boards having long-length shapes disposed along thedisplay panel; light emitting elements arrayed on each of the pluralityof mount boards in a longitudinal direction of each of the plurality ofmount boards, the light emitting elements emitting light toward thedisplay panel from behind the display panel, and being arranged in amatrix shape along the display panel; a back surface board on which theplurality of mount boards is stuck by an adhesive member; and areflective sheet mounted to the back surface board, the reflective sheethaving holes that allow the light emitting elements to pass through atpositions corresponding to the light emitting elements, and reflectingthe light emitted from the light emitting elements toward the displaypanel, wherein each of the plurality of mount boards is constituted of aflexible wiring board.
 2. The display device according to claim 1,wherein a thickness of the flexible wiring board ranges from 0.01 mm to0.05 mm, inclusive.
 3. The display device according to claim 1, whereina white solder resist having a light reflectance of 95% or more isapplied to a surface, on which the light emitting elements are arrayed,among a plurality of surfaces included in each of the plurality of mountboards.
 4. The display device according to claim 3, wherein when a sizeof each of the light emitting elements in a top view ranges from 1 mmsquare to 3 mm square, inclusive, a size of each of the holes in the topview ranges from 10 mm square to 15 mm square, inclusive.
 5. The displaydevice according to claim 1, wherein the reflective sheet is stuck onthe back surface board by the adhesive member, and an end of each of theplurality of mount boards and an end of each of holes, among the holes,corresponding to the end of each of the plurality of mount boardsoverlap each other when viewed from the top.
 6. The display deviceaccording to claim 1, further comprising a relay board having along-length shape for supplying power to the light emitting elements,wherein on a surface of the back surface board on which the plurality ofmount boards is stuck, a recess depressed toward an opposite surface ofthe surface on which the plurality of mount boards is stuck is providedin a direction perpendicular to the longitudinal direction of each ofthe plurality of mount boards, and when the relay board is placed in therecess and is placed at an end of each of the plurality of mount boardslocated in the recess, the relay board is electrically connected witheach of the plurality of mount boards.